A dictatorship of any sort wont get you much different than capitalism does: capitalism has the effect that it does because it creates a situation where power concentrates (because wealth is generally a proxy for power, and having a lot of capital under capitalism allows you to more easily obtain more of the finite pool of it), so that decisions are made that benefit the few with power while the many without much of it suffer the negative externalizes of those decisions, that the wealth of the powerful insulates them from. A dictator represents simply skipping to the end-state of that, where power is highly concentrated among one person and those that directly enable them. They still will make decisions that benefit themselves at the cost of the well being of everyone else, because people are selfish that way. Even if you somehow get a person that somehow cares more about everyone else than themself, that person wont be dictator forever, and since that mentality isnt the norm for dictators, odds are soon enough you'll end up with an "unenlightened" dictatorship again.

It would still be industrialized and still be far too numerous not to affect the ecosystem.

You can’t have eight billion people on the planet and a healthy environment. They’re mutually exclusive. The more people there are the more resources we need, and the less are available for other species.